Characterization of an Electronic Corneal Prosthesis System.

PURPOSE: Corneal opacity is a leading cause of reversible blindness worldwide. An electronic corneal prosthesis, or intraocular projector, could potentially restore high-quality vision without need for corneal clarity. MATERIALS AND METHODS: Four intraocular projection systems were constructed from commercially available electronic components and encased in biocompatible plastic housing. They were tested for optical properties, biocompatibility, heat dissipation, waterproofing, and accelerated wear. A surgical implantation technique was developed. RESULTS: Intraocular projectors were produced of a size that can fit within the eye. Their optics produce better than 20/200 equivalent visual acuity. MTT assay demonstrated no cytotoxicity of devices in vitro. Temperature testing demonstrated less than 2°C increase in temperature after 1 h. Three devices lasted over 12 weeks under accelerated wear conditions. Implantation surgery was demonstrated via corneal trephination insertion in a cadaver eye. CONCLUSION: This is the first study to demonstrate and characterize fully functional intraocular projection systems. This technology has the potential to be an important new tool in the treatment of intractable corneal blindness.

Microbiota evaluation of patients with a Boston type I keratoprosthesis treated with topical 0.5% moxifloxacin and 5% povidone-iodine.

PURPOSE: To evaluate the efficacy of a prophylactic regimen of daily topical 0.5% moxifloxacin and 5% povidone-iodine (PI) in patients with Boston type I keratoprosthesis (KPro) and to assess the applicability of a novel molecular diagnostic technique to analyze the ocular surface microbiota in these patients. METHODS: Ten patients had their inferior conjunctival fornix sampled for standard culture methods before the addition of topical 5% PI to the prophylactic regimen and were considered the control group (group 1). The inferior conjunctival fornix and the KPro-donor cornea interface of 10 patients treated with the mentioned prophylactic regimen were sampled and analyzed by standard culture methods and using a polymerase chain reaction/electrospray ionization mass spectrometry assay (group 2). RESULTS: Samples from the inferior conjunctival fornix were positive for coagulase-negative staphylococcus in 3 patients and for Aerobasidium pullulans in 1 patient in group 1. The inferior conjunctival fornix and the KPro-donor cornea interface scrapings were positive for coagulase-negative staphylococcus in 2 patients and 1 patient, respectively, in group 2. No bacteria and fungi growth were detected in any patient from group 2 with the molecular diagnostic approach. None of the patients with culture-positive results developed keratitis or endophthalmitis during the study. CONCLUSIONS: Topical 0.5% moxifloxacin associated with topical 5% PI is an effective prophylactic regimen in patients with Boston type I KPro. The molecular diagnostic approach using serial polymerase chain reaction and mass spectrometry was comparable with standard microbiologic techniques as a surveillance tool in these patients.

Silk film topography directs collective epithelial cell migration.

The following study provides new insight into how surface topography dictates directed collective epithelial cell sheet growth through the guidance of individual cell movement. Collective cell behavior of migrating human corneal limbal-epithelial cell sheets were studied on highly biocompatible flat and micro-patterned silk film surfaces. The silk film edge topography guided the migratory direction of individual cells making up the collective epithelial sheet, which resulted in a 75% increase in total culture elongation. This was due to a 3-fold decrease in cell sheet migration rate efficiency for movement perpendicular to the topography edge. Individual cell migration direction is preferred in the parallel approach to the edge topography where localization of cytoskeletal proteins to the topography's edge region is reduced, which results in the directed growth of the collective epithelial sheet. Findings indicate customized biomaterial surfaces may be created to direct both the migration rate and direction of tissue epithelialization.

Silk film culture system for in vitro analysis and biomaterial design.

Silk films are promising protein-based biomaterials that can be fabricated with high fidelity and economically within a research laboratory environment (1,2). These materials are desirable because they possess highly controllable dimensional and material characteristics, are biocompatible and promote cell adhesion, can be modified through topographic patterning or by chemically altering the surface, and can be used as a depot for biologically active molecules for drug delivery related applications (3-8). In addition, silk films are relatively straightforward to custom design, can be designed to dissolve within minutes or degrade over years in vitro or in vivo, and are produce with the added benefit of being transparent in nature and therefore highly suitable for imaging applications (9-13). The culture system methodology presented here represents a scalable approach for rapid assessments of cell-silk film surface interactions. Of particular interest is the use of surface patterned silk films to study differences in cell proliferation and responses of cells for alignment (12,14). The seeded cultures were cultured on both micro-patterned and flat silk film substrates, and then assessed through time-lapse phase-contrast imaging, scanning electron microscopy, and biochemical assessment of metabolic activity and nucleic acid content. In summary, the silk film in vitro culture system offers a customizable experimental setup suitable to the study of cell-surface interactions on a biomaterial substrate, which can then be optimized and then translated to in vivo models. Observations using the culture system presented here are currently being used to aid in applications ranging from basic cell interactions to medical device design, and thus are relevant to a broad range of biomedical fields.

Vitreoretinal surgery in the setting of permanent keratoprosthesis.

OBJECTIVES: To evaluate the surgical management of vitreoretinal pathology in patients with a permanent Boston Type 1 keratoprosthesis (hereafter referred to as a KPro) in the era of small-gauge vitrectomy techniques. METHODS: Retrospective review of 23 small-gauge vitreoretinal surgical procedures during or after Dohlman-Doane KPro placement in 14 eyes. RESULTS: Established and innovative techniques were used, including sutureless small-gauge vitrectomy, temporal positioning of surgeon, long-term tamponades, and exploratory endoscopy. Retro-KPro membranes formed less frequently when vitrectomy was performed during KPro placement. Anatomical goals were achieved, and no serious complications directly resulted from these techniques. Visual acuity, frequently limited by preexisting pathology, improved in most cases. CONCLUSIONS: Modern posterior segment surgical techniques, including small-gauge sutureless vitrectomy, can be effectively used for patients with a permanent KPro. Vitrectomy and glaucoma tube revision by a team of subspecialists at the time of KPro placement may reduce subsequent complications.

Silk fibroin as a biomaterial substrate for corneal epithelial cell sheet generation.

PURPOSE: To evaluate a silk fibroin (SF) biomaterial as a substrate for corneal epithelial cell proliferation, differentiation, and stratification in vitro compared with denuded human amniotic membrane (AM). METHODS: Primary human and rabbit corneal epithelial cells and immortalized human corneal limbal epithelial cells were cultured on the SF and denuded AM, respectively. The biological cell behavior, including the morphology, proliferation, differentiation, and stratification, on the two substrates was compared and analyzed. RESULTS: Corneal epithelial cells can adhere and proliferate on the SF and denuded AM with a cobblestone appearance, abundant microvilli on the surface, and wide connection with the adjacent cells. MTT assay showed that cell proliferation on denuded AM was statistically higher than that on SF at 24 and 72 hours after plating (P = 0.001 and 0.0005, respectively). Expression of ΔNp63a and keratin 3/12 was detected in primary cell cultures on the two substrates with no statistical difference. When cultured at the air-liquid interface for 7 days, cells on SF could form a comparable stratified graft with a 2- to 3-cell layering, which compared similarly to AM cultures. CONCLUSIONS: SF, a novel biomaterial, could support corneal epithelial cells to proliferate, differentiate, and stratify, retaining the normal characteristic epithelium phenotype. Compared with AM, its unique features, including the transparency, ease of handling, and transfer, and inherent freedom from disease transmission, make it a promising substrate for corneal wound repair and tissue-engineering purposes.

Effect of hydration on silk film material properties.

Effects of hydration on silk fibroin film properties were investigated for water-annealed and MeOH-treated samples. Hydration increased thickness by 60% for MeOH-immersed films, while water-annealed samples remained constant. MeOH-immersed films showed an 80% mass loss due to water, while water-annealed lost only 40%. O(2) permeability was higher in MeOH-immersed films with Dk values of 10(-10) (mL O(2) x cm) x (cm(-1) x s(-1) x mmHg(-1)), while those of water-annealed films reached only one fifth of this value. All films showed a decrease in Young's modulus and increased plastic deformation by two orders of magnitude when submerged in saline solution. FT-IR showed that beta-sheet content in water-annealed films increased with increasing water vapor pressure, while MeOH-immersed films showed no change.